    [Patent document 1] JP-2007-301101 A (US2007/0265540)    [Patent document 2] JP-2001-346769 A (US2001/0051773)
There is conventionally existing a system in a moving object such as a vehicle to measure an electrocardiography signal from a steering wheel to thereby determine an irregular heartbeat (i.e., arrhythmia) (refer to Patent document 1). This system measures an electrocardiography signal of “Lead I” from the both hands which grasp the steering wheel.
In addition, there is known a circulatory state monitor apparatus which can determine a patient's circulatory state with an irregular heartbeat detected from an electrocardiography, a pulse waveform resulting from pressure to a cuff, and a pulse waveform from a photoelectric sensor (refer to Patent document 2).
However, the conventional system is apt to be affected by the influence of the noise etc.; thus, it is not so easy to determine the danger on user's living body state accurately.